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Narayanswami Sreeram

Publications and source records attributed to Narayanswami Sreeram.

At least 19 recordsLinked to original sources
PubMed2006

Superior vena cava stenting and transvenous pacemaker implantation (stent and pace) after the Mustard operation.

The Mustard operation for transposition of the great arteries is associated with good long-term survival. Typical complications at follow-up include progressive loss of sinus node function requiring permanent pacemaker implantation, and systemic venous pathway obstruction often precluding a transvenous approach to pacing. We report on 7 patients (median age 14.1; range 5-19) with bradyarrhythmia requiring permanent pacemaker implantation with associated stenosis (n = 6) or occlusion (n = 1) of the superior vena cava, in whom stent implantation relieved the obstruction and facilitated subsequent transvenous permanent pacing. In five of them stenting and pacemaker implantation were performed during a single procedure; two patients underwent elective pacemaker implantation 6 weeks later. In one patient the pacemaker had to be explanted due to pacemaker pocket infection. In the others the follow-up has been uneventful, with excellent chronic pacing thresholds and appropriate sensing. Two patients have had their generator replaced electively.We conclude that stenting of the SVC stenosis allows implantation of transvenous pacemaker leads with good intermediate term results in patients with a Mustard operation for transposition of the great arteries.

Adolescent↗
PubMed2006

Force measurements of human embryonic stem cell-derived cardiomyocytes in an in vitro transplantation model.

Human embryonic stem cell (hESC)-derived cardiomyocytes have been suggested for cardiac cell replacement therapy. However, there are no data on loaded contractions developed by these cells and the regulation thereof. We developed a novel in vitro transplantation model in which beating cardiomyocytes derived from hESCs (line H1) were isolated and transplanted onto noncontractile, ischemically damaged ventricular slices of murine hearts. After 2-3 days, transplanted cells started to integrate mechanically into the existing matrix, resulting in spontaneous movements of the whole preparation. Preparations showed a length-dependent increase of active tension. In transplanted early beating hESC-derived cardiomyocytes, frequency modulation by field stimulation was limited to a small range around their spontaneous beating rate. Our data demonstrate that this novel in vitro transplantation model is well suited to assess the mechanical properties and functional integration of cells suggested for cardiac replacement strategies.

Animals↗
PubMed2006

Wireless Holter transmission in suspected dysrhythmias.

BACKGROUND: In patients with a history of possible dysrhythmias, documentation of an episode is mandatory before any form of treatment is given. Holter recordings with wireless telemetry offer the possibility of continuously recording electrocardiograms for days or even weeks with instantaneous analysis of the data in the physician's office. METHODS: Thirty-seven patients (20 male; median age, 8.4 years; range, 0.1-22 years), were investigated by using a telemetric Holter system (M120, Schiller, Switzerland), that is, intermittent transmission of the electrocardiographic data to a remote server using cell phone frequencies, with a median duration of the recordings of 6.5 days (range 1-42 days). RESULTS: Recording quality was sufficient in all patients. Problems were related to electrode disconnections only, which were adjusted by contacting the patients. Twenty-eight of 37 recordings showed decisive findings. Of the 28 patients, no treatment was indicated in 16 patients, as subjective symptoms did not correlate with dysrhythmias; psychotherapy was indicated in 2 patients; antiarrhythmic medication was initiated or intensified in 5 patients; radiofrequency ablation was successfully performed in 5 patients; and 1 patient received an ICD. In 6 of 9 patients with negative Holter findings, a loop recorder implantation (Medtronic, Minneapolis, Minn) was indicated. In 1 patient, no dysrhythmias were recorded; however, when invasively investigated, ventricular tachycardia was detected and successfully treated by radiofrequency ablation. In 2 patients, no decision has been made to date. CONCLUSIONS: Wireless Holter recordings are useful in detecting dysrhythmias with rare occurrence, are less expensive and less invasive compared with implantable loop recorders, and offer the patient rather wide geographic ranges with sufficient signal quality.

Adolescent↗
PubMed2006

Who benefits from intervention in, as opposed to screening of, overweight and obese children?

AIMS: StEP TWO is a school- and family-based intervention consisting of extra lessons, healthy nutrition and physical education for overweight and obese children in primary schools, aimed at reducing body mass index by maintenance or reduction of weight, and improving motor abilities. We analysed differences in changes in anthropometric, cardiovascular and obesity parameters between children who underwent intervention, non-participants in intervention, and controls. METHODS: Anthropometric data and waist circumference were recorded for 1678 children; body mass index and body mass index-standard deviation score were calculated. Blood pressure was measured after 5 minutes at rest. 121 overweight and obese children enrolled at 3 schools involved in programmes of intervention were invited to take part; 40 of them completed the programme from November 2003 to July 2004. Of these overweight children, 74 were invited, but did not take part. As controls, we enrolled 155 overweight and obese children from 4 other schools. RESULTS: After the programme, the children involved in intervention showed a lower increase in the body mass index (0.3 plus or minus 1.3 versus 0.7 plus or minus 1.2 kilograms per metre squared) and an approximately three times higher diminution of the body mass index-standard deviation score in comparison with their controls (-0.15 plus or minus 0.26 versus 0.05 plus or minus 0.27). Systolic blood pressure was significantly lowered by 9.5 plus or minus 19.6 millimetres of mercury in those involved in intervention, but increased in the control group by 0.5 plus or minus 16.5 millimetres of mercury. Among those invited but not participating, the increase of the body mass index (0.5 plus or minus 1.3 kilograms per metre squared) was less, and the reduction of the body mass index-standard deviation score (-0.09 plus or minus 0.31) and systolic blood pressure (-5.3 plus or minus 15.6 millimetres of mercury) was higher than in the control group. Overweight but not obese children seem to benefit from a screening examination alone. CONCLUSIONS: Early preventive measures in schools are necessary and effective for overweight and obese primary school children. The screening itself seems also to have a minor positive effect, especially for overweight children. Sustainability of the observed improvements over a longer period remains to be confirmed.

Blood Pressure↗
PubMed2005

Outcome of muscle and bone development in congenital heart disease.

Muscles and bones of patients with congenital heart disease (CHD) are subject to various potentially deleterious influences during growth. The aim of the present study was to analyse the outcome of bone and muscle parameters in adolescents and young adults with a spectrum of CHD. Bone and muscle parameters of the forearm were examined at two standard sites, 4% and 65%, in 29 adolescents and young adults with CHD, aged 14-24 years, by quantitative computed tomography. For the entire study population, bone and muscle parameters did not deviate significantly from the reference values except for age- and gender-corrected body height (ASDS-height: -0.6+/-1.2, p=0.01). Both age- and gender- and height- and gender-corrected (HSDS) abnormal bone mass (BMC) was found at the distal radius in patients with Fontan repair (ASDS-BMC4%: -1.5+/-0.9, p=0.008; HSDS-BMC4%: -1.2+/-1.0, p=0.05) and in those in NYHA class III (ASDS-BMC4%: -1.3+/-0.4, p=0.001; HSDS-BMC4%: -1.4+/-0.5, p=0.004). There was minimal overlap between Fontan patients (n=6) and NYHA class III (5 Fontan patients were in NYHA class I or II). In conclusion, most patients with CHD show a normal muscle and bone development in proportion to their reduced body height. Further follow-up is required to determine whether patients in a worse clinical status (NYHA III) and those with single ventricle physiology are at increased risk of osteoporosis and fractures.

Adolescent↗
PubMed2005

Implantable cardioverter defibrillator implantation in children in The Netherlands.

UNLABELLED: To evaluate the indications, underlying cardiac disorders, efficacy and complications involved with implantable cardioverter-defibrillators (ICDs) in paediatric patients in The Netherlands, the records of all patients aged 18 years or younger who underwent ICD placement were reviewed retrospectively. Between January 1995 and September 2002, 23 patients (11 males, 12 females; median age 12 years, range 6 months to 16 years) underwent ICD implantation. The ICD was implanted for aborted sudden cardiac death ( n = 14), syncope ( n = 5) or for primary prevention of sudden cardiac death ( n = 4). Underlying cardiac disorders were electrical diseases ( n = 16), hypertrophic or dilated cardiomyopathy ( n = 4) and congenital cardiac malformations ( n = 3). Five patients had an epicardially placed ICD, while 18 underwent a transvenous approach. The generator was placed in an abdominal position in eight patients, whereas it was placed in the subpectoral region in 15. There was no early mortality. Median hospital stay was 5 days (range 2-30 days). Median follow-up time was 29 months (range 1 month to 7 years). Seven patients experienced an inappropriate shock after a median period of 7 months; five patients an appropriate shock after a median period of 3 months. The reasons for inappropriate shock were supraventricular tachycardia ( n = 1), sinus tachycardia ( n = 4) or T-wave sensing (n = 2). One patient with malignant long QT syndrome died of intractable arrhythmias and irreversible cardiomyopathy. Generator replacement was necessary in four patients after 28, 44, 51 and 54 months respectively. CONCLUSION: Implantable cardioverter-defibrillator implantation in paediatric patients is a safe procedure with a good medium-term outcome. The most serious problem is the occurrence of a significant number of inappropriate shocks.

Adolescent↗
PubMed2005

Abdominal implantation of loop recorders in infants and children.

Implantable loop recorders have an important role in establishing symptom-rhythm correlation in adults with recurrent syncope or palpitations. The standard location of these devices is in a subcutaneous prepectoral pocket. As the device is bulky, this is not an ideal location in young patients. We report a technique of abdominal implantation of this device in 10 consecutive infants and children, achieving an excellent cosmetic result and diagnostic-quality electrograms at follow-up.

Abdominal Wall↗
PubMed2005

Data from the StEP TWO programme showing the effect on blood pressure and different parameters for obesity in overweight and obese primary school children.

UNLABELLED: Obesity in childhood, which is associated with cardiovascular risk factors such as hypertension, is on the increase. Countermeasures are necessary. In this paper, we present the baseline and final data from the StEP TWO programme, a prospective study to prevent overweight and obesity in primary schools. METHODS: We recorded and calculated, from 1689 children, anthropometric data, including analyses of bioelectric impedance, waist and hip circumferences, body mass index and its standard deviation, and the ratio of waist to hip. Blood pressure was measured after 5 minutes at rest. From the three schools involved in a programme of intervention, 121 children were invited to take part, and 40 (33.1 per cent) completed the programme. The effect was compared with 155 overweight and obese children identified at the 4 control schools. RESULTS: 830 (49.5 per cent) boys and 848 girls (50.5 per cent) took part. Their mean age was 8.2 plus or minus 1.3 years, their height was 1.31 plus or minus 0.09 metres, they weighed 30.0 plus or minus 8.2 kilograms, and their mean index of body mass was 17.1 plus or minus 2.9 kilograms per metre squared. Of the children, 7.3 per cent were obese, 10.4 per cent were overweight, 75.7 per cent had normal weights, and 6.6 per cent were underweight. Resting hypertension was observed in 2.3 per cent of the children. Increased blood pressure was associated with a higher body weight, body mass index, standard deviation score for body mass index, and waist and hip circumferences (each p < 0.001), but not with the ratio of waist to hip. Hypertension at rest was also found in 11.0 per cent of obese children, 4.4 per cent of those who were overweight, 1.2 per cent of those with normal weight, and 1.0 per cent of underweight children (p < 0.001). After the intervention, the increase of the body mass index tended to be lower in those in whom we had intervened (p = 0.069), and in these the decrease of the standard deviation score for body mass index was significantly higher (p = 0.028). Systolic blood pressure was reduced by about 10 millimetres of mercury in those in whom we had intervened (p = 0.002), while there were no changes in the control group. Diastolic blood pressure was lowered by 3 millimetres of mercury, but this was not significant. CONCLUSION: Obese children had the highest values for systolic and diastolic blood pressure. Increased levels of blood pressure are associated with other parameters of obesity, such as the circumference of the waist and hip. Early preventive measurements in childhood are necessary, and appropriate intervention appears to be effective.

Blood Pressure↗
PubMed2004

Predictors of sudden cardiac death after Mustard or Senning repair for transposition of the great arteries.

OBJECTIVES: The goal of this research was to identify predictors for sudden death (SD) in patients with transposition of the great arteries (TGA) who have undergone atrial inflow repair. BACKGROUND: Sudden death is the most common cause of late death after atrial inflow repair of TGA. Little is known about the predictors of SD. METHODS: This was a retrospective, multicenter, case-controlled study. We identified 47 patients after Mustard's or Senning's operation who experienced an SD event (34 SD, 13 near-miss SD). Each patient was matched with two controls with the same operation, but without an SD event. Information on numerous variables before the event was obtained and compared with controls at the same time frame. RESULTS: Presence of symptoms of arrhythmia or heart failure at most recent follow-up and history of documented arrhythmia (atrial flutter [AFL]/atrial fibrillation [AF]) were found to increase the risk of SD. Electrocardiogram (ECG), chest X-ray, and Holter ECG findings were not predictive of SD. Neither medication nor pacing was found to be protective. Most SD events (81%) occurred during exercise. Ventricular tachycardia/ventricular fibrillation were the recorded rhythm during SD in 21 of 47 patients. CONCLUSIONS: Presence of symptoms and documented AFL/AF are the best predictors of SD in TGA patients. Patients with these findings should be further evaluated for risk of SD.

Arrhythmias, Cardiac↗
PubMed2004

Total Anomalous Pulmonary Vein Connection: Diagnosis, Management, and Outcome.

Total anomalous pulmonary venous connection (TAPVC) is a congenital cardiac malformation that requires surgical therapy. The majority of patients will present either in the neonatal period or early infancy, with cyanosis and signs of cardiac failure (eg, tachypnea, feeding difficulties, diaphoresis, failure to thrive). Surgical repair is best carried out on diagnosis, as an elective procedure, to avoid potential long-term problems associated with right heart volume and pressure overload, or long-standing cyanosis. Occasionally, in severely sick patients with obstructed forms of pulmonary venous drainage, emergency surgical repair may be required. The operative mortality for isolated TAPVC using current management techniques is less than 10%, and the long-term outlook for the majority of patients is excellent. In contrast, patients with associated complex cardiac malformations have a less favorable prognosis, determined both by the need to palliate the associated defects and the often underdeveloped pulmonary vascular bed. The major long-term complication is pulmonary venous obstruction, which may be recurrent in up to 10% of patients. This requires aggressive management strategies, involving reoperation, and balloon angioplasty or stent implantation. The prognosis for these patients is determined by the number of vessels involved and the degree of stenosis, which can often be recurrent and progressive. Late tachy- and bradyarrhythmias have also been described, requiring antiarrhythmic drug therapy or pacemaker implantation, emphasizing the need for continued long-term follow-up of all patients with TAPVC.

Journal Article↗
PubMed2004

Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia in children aided by the LocaLisa mapping system.

AIMS: In young patients, slow pathway ablation for treatment of atrioventricular nodal reentrant tachycardia (AVNRT) carries a small but definite risk of permanent AV block. The aim was to assess the efficacy of slow pathway ablation aided by the LocaLisa mapping system. PATIENTS AND METHODS: Radiofrequency (RF) modification of the slow AV nodal pathway was performed in 26 children < 19 years of age (median age 9.8 years, range 3-18.9). Three measures to limit the risk of AV block were applied: (1) use of LocaLisa, a non-fluoroscopic mapping system, to determine and mark the location of the AV node/His bundle axis, and monitor ablation catheter position, (2) continuous atrial stimulation during RF delivery to monitor AV conduction, and (3) gradual increase of RF power during RF ablation. RESULTS: AVNRT was rendered non-inducible in all patients. Dual AV physiology was abolished in 24/26 patients; 2 patients had single atrial echoes at the end of the procedure. At follow-up, AVNRT recurred in 3 patients (including the above 2), necessitating a second procedure. The median number of RF applications was 4 (3-8); median fluoroscopy time was 16 (7-33)min. One patient developed transient second-degree AV block, with full recovery within 6 weeks of the procedure. CONCLUSIONS: RF modification of the slow AV nodal pathway in children can be safely accomplished, achieving the ideal end-point of abolishing dual AV physiology, aided by use of the LocaLisa mapping system.

Adolescent↗
PubMed2004

Is routine echocardiography valuable after uncomplicated catheter ablation in children?

We determined the clinical value of routine transthoracic echocardiography performed after catheter ablation of supraventricular tachyarrhythmias in children. Between April 1996 and December 2003, 253 children, of whom 135 male, with the overall group having a median age of 9, ranging from 0.1 to 19 years, underwent 280 uncomplicated radiofrequency catheter ablation procedures for supraventricular tachyarrhythmias at three institutions. In every child, transthoracic Doppler echocardiography was performed before and after the procedure. The pre-ablation transthoracic echocardiograms were normal in all, and this was one of the criterions for inclusion. The post-ablation echocardiogram showed a disorder in four asymptomatic patients. In one patient, with focal atrial tachycardia, ablated via a retrograde aortic approach, there was mild aortic valvar insufficiency. This had resolved 6 months later. Pericardial effusions developed in 3 other children. In 2 the effusions resolved spontaneously but 1 patient required pericardial drainage. This same patient also developed clinically asymptomatic mild aortic insufficiency, which resolved spontaneously within 6 months. Routine echocardiography after uncomplicated catheter ablation procedures is of clinical value, and is especially indicated when a retrograde aortic approach has been used.

Adolescent↗
PubMed2004

Ventricular preexcitation associated with dilated cardiomyopathy: a causal relationship?

Over a six year period, we identified four children with dilated cardiomyopathy associated with ventricular preexcitation, three in the absence of any documented tachyarrhythmias, and one with but a solitary episode of tachyarrhythmia. None of them had another identifiable aetiology for the cardiomyopathy. Based on the 12 lead electrocardiogram, and/or invasive electrophysiologic studies, we localised the accessory pathways to the right atrioventricular groove in all patients. We commenced antifailure medications in two of the four patients, but did not produce any measurable improvement in ventricular function. Catheter ablation was performed in two patients, with resolution of the cardiomyopathy. The ventricular preexcitation disappeared spontaneously in one child during follow-up, again with resolution of cardiomyopathy. The youngest patient continues to receive antifailure medications, albeit without improvement. We suggest, therefore, that dilated cardiomyopathy of reversible nature is associated with manifest ventricular preexcitation, even in the absence of sustained arrhythmias.

Adolescent↗
PubMed2004

Endocardial pacemaker implantation in infants weighing < or = 10 kilograms.

Epicardial pacemaker implantation is the most common approach for small children requiring pacemaker implantation, though it is not free from complications. This article reviews the experience with endocardial pacemaker implantation, as an alternative approach, in children < or =10 kg at two centers. Thirty-nine children, median age 3.8 months (2 days-35 months), weight 4.6 kg (2.3-10 kg) underwent endocardial permanent pacing (VVI/R in 38, DDDR in 1). Indications for pacing were complete heart block (CHB) in 34 (congenital in 21, postsurgical in 12, congenitally corrected transposition of the great arteries 1), long QT syndrome in 3, and sinus bradycardia in 2 children. Two children with postsurgical CHB died 7 days and 3 weeks after implantation, respectively, due to heart failure and septicemia, despite appropriate pacemaker therapy. Over a median follow-up of 4.3 years (9 months-15.3 years), 12 patients underwent 18 generator replacements. Five patients were upgraded to physiological pacing. Ten patients underwent 12 ventricular lead advancements. Ventricular lead extraction was attempted 11 times in nine patients and succeeded 10 times. Two patients were converted to epicardial dual chamber systems. Two prepectorally placed generators required resiting due to threatened skin necrosis. Infective endocarditis on the lead, 9 months postimplant required removal of the system in one patient. The subclavian vein was found to be asymptomatically thrombosed in four patients. Endocardial permanent pacing is feasible and effective in children < or = 10 kg and an acceptable alternative to epicardial pacing.

Arrhythmia, Sinus↗
PubMed2003

Global impairment of cardiac autonomic nervous activity late after the Fontan operation.

BACKGROUND: Atrial tachyarrhythmia is a common cause of morbidity and mortality in patients with univentricular physiology undergoing the Fontan operation. We examined cardiac autonomic nervous activity, a predictor of arrhythmia and sudden death in other cardiovascular disease, in patients late after the Fontan operation, employing heart rate variability (HRV) and baroreflex sensitivity. METHODS AND RESULTS: We measured HRV and baroreflex sensitivity in 22 consecutive patients (8 male, age 26+/-9 years) who had undergone the Fontan operation 13+/-6 years previously, and 22 age- and sex-matched healthy controls. Fontan patients had significantly lower HRV (P<0.0001). Baroreflex sensitivity was measured by the alpha-index method (square root of ratio of RR interval spectral power to systolic blood pressure (SBP) spectral power, in the LF and the HF band) and was also significantly depressed in the Fontan group (P<0.0001 for both). Both low frequency (LF) and high frequency (HF) components of HRV were reduced in the Fontan patients (P<0.0001), but there was interindividual variation so that the LF/(LF+HF) ratio may be high, normal, or low, and decreased with increasing right atrial dimensions (r=-0.62, P=0.006). Patients with a history of sustained atrial arrhythmia had a stronger baroreflex than those without (P=0.005). CONCLUSIONS: Autonomic nervous control of the heart is markedly deranged in patients late after the Fontan operation, with reduced HRV and baroreflex sensitivity. A relative suppression of the sympathetic-compared with the parasympathetic-system was observed in patients with marked right atrial dilation within the Fontan group. Furthermore, stronger baroreflexes were seen in Fontan patients in association with a higher incidence of sustained atrial tachyarrhythmia, implying that sinus node dysfunction is unlikely to be the dominant mechanism. Additional studies are clearly required to examine the prognostic importance of impaired BRS and HRV in these patients.

Adolescent↗